Fatigue evaluation of power devices

Semiconductors are solids whose electrical conductivity is intermediate between that of a conductor and an insulator. Semiconductor devices are active devices that consume, accumulate, and discharge the supplied electric power. They are used as electronic or power devices. The former are employed in the control systems of electrical products such as mobile phones and computers, which are controlled by electrical currents. Power devices are also controlled by currents, but these currents are the main energy sources of the electrical products. Therefore, the Joule heating generated in power devices is much larger than that generated in electronic devices. This heating is concentrated at a single point on the body of the device, where deterioration due to strain is localized. There is an increasing need for power devices that are lightweight and compact. However, reducing the weight of power devices would result in reduced stiffness, and greater compactness would results in increased current density, which, in turn, would increase the temperature threshold of the device. Thus, to realize lightweight, compact power devices with sufficient reliability, multiphysics fatigue analysis techniques that simultaneously consider electricity, heat, and stress should be developed. In the literature, a FEM-based lifetime model for AI wire has been derived. Methods for thermal analysis of power devices considering the wire connection layout have been analyzed using 3D FEM simulation, and a FEM-based evaluation method has been presented. The thermal fatigue reliability of power devices has also been described. In one such study, coupled thermal-electrical and thermal-structural analyses were performed to evaluate the fatigue behavior of these devices. Then, crack propagation in the device was evaluated. In the present study, to accurately predict the fatigue properties of power devices, evaluation techniques based on multiphysics analysis are proposed.